Biostats (lecture)

Question 1

What is validity vs. reliability?

Answer 1

Validity: Does it give you the right answer?
Reliability: Is the right answer repeatable?

Question 2

What is the formula for sensitivity?

Answer 2

TP/(TP+FN)

Question 3

What is the formula for specificity?

Answer 3

TN/(TN+FP)

Question 4

What is the formula for positive predictive value?

Answer 4

TP/(TP+FP)

Question 5

What is the formula for negative predictive value?

Answer 5

TN/(TN+FN)

Question 6

How are negative predictive value and prevalence related?

Answer 6

Inversely, the higher the prevalence, the lower the NPV - more false negative

Question 7

How are positive predictive value and prevalence related?

Answer 7

Directly, the higher the prevalence, the higher the PPV - more true positives

Question 8

What is the formula for positive likelihood ratio?

Answer 8

+LR = Sensitivity / (1-specificity)

Question 9

What is the formula for negative likelihood ratio?

Answer 9

• LR = (1 - sensitivity) / specificity

Question 10

Practice problems for using + LR and - LR…

Answer 10

medcalc.com/bayes.html